The present invention relates to an endless belt. More particularly, it relates to a method of producing an original paper conveyor belt and an automatic original paper feeding apparatus (automatic document feeder (ADF)) equipped with the same belt, applied to an apparatus such as a copying machine or a recording apparatus.
The automatic original paper feeding apparatus (automatic document feeder (ADF)) equipped in a copying machine, for example, is provided with an original paper conveying belt which conveys an original paper placed thereon with the image surface side to be copied facing downward to the belt surface to a predetermined position on a contact glass. Such a conveyor belt is wound around and spanning between a pair of belt rollers that drive the belt to convey the original paper from the paper feed portion to the exposure position on the contact glass. The conveyor belt stops when the original paper comes to the exposure position where the original paper is exposed and scanned. After the exposure of the original paper, the conveyor belt is again driven to discharge the original paper from the exposure position on the contact glass. When both surface sides of the original paper are to be copied, the original paper is reversed and reconveyed to the contact glass after one surface side is copied.
The conventional original paper conveying belt comprises an endless belt having a white colored outer surface side made of sole rubber material on which the original paper is placed. The conveyor belt may be constructed as an elastic coreless belt or comprise a nonelastic core belt layer made from a woven cloth or yarn.
With regard to the coreless belt made from sole rubber material, the belt is relatively easy to produce. However, with regard to the endless belt having a core layer, the belt is produced by such a way that, first an elastic layer is coated on an endless core material, then the elastic layer is dried and the coating step and the drying step are repeated to obtain a predetermined thickness of the elastic layer of the belt.
The coreless rubber belt is economical but easily damaged since the durability thereof is low due to low hardness of the rubber. Besides, the belt has to be relatively thick to strengthen the belt, which makes the belt heavy and increases the load of the belt drive system.
On the other hand, with regard to the conventional complex belt having a core layer, the belt is strengthened by the core without increasing the weight thereof. However, the conventional belt has seam lines on the outer surface thereof. The belt is soiled with dirt along the seam lines. The soiled line is copied on the copying paper, which degrades the quality of the copy. Also, the seam portion is weak so that the belt is apt to be torn from and along the seam line. Further, the seam line periodically creates a noise at the time when the seam line passes the member which is in contact with the conveyor belt.
In order to obviate the problems mentioned above, various techniques for producing a seamless belt having a core have been proposed. However, proposed techniques are not satisfactory as described below.
The endless belt with core layer is manufactured by coating an elastic resin material such as rubber on the surface of endless core member. The elastic coating layer needs a predetermined thickness. Therefore, the coating step for coating the elastic material on the core and the drying step for drying the elastic material have to be repeated three to five times to reach the aimed thickness, which requires a long time to manufacture the belt and impairs the productivity thereof. More precisely, the thickness of the coating layer at one time is about 0.05 mm to 0.1 mm while the required thickness of the elastic layer of the belt is about 0.2 mm to 0.25 mm, which requires several repetitions of the coating and drying steps. It takes about twenty four hours for drying the coating layer in one drying step. Therefore, it takes about one week for manufacturing one conveyor belt repeating the coating and drying of the elastic layer, which lowers the efficiency of mass production of the conveyor belt. Also, in the drying process, dust in the air is apt to attach to the surface of the liquid coating layer, which impairs the outer view of the belt and increases the ratio of defective products.
Generally, soil or stain on the conveyor belt is cleaned by using a specific solvent such as alcohol. However, with regard to the conventional coating type conveyor belt having a core layer mentioned above, the soil or stain is not completely removed but spread entirely over the belt surface instead, which impedes the reuse of the conveyor belt. The cause of this unremovable soil or stain is supposed that a solvent used in the coating step sputters on the belt surface and makes a porous surface there in which dirt or soil is permeated and enclosed unsweepably.
On the other hand, conventionally, a complex sheet member comprising a nonexpansible core member and an elastic laminate layer is developed. However, technique to constitute an endless conveyor belt made from such a complex member has not been developed yet.